Handicapped or injured persons confined to wheelchairs are particularly vulnerable when riding in public transportation vehicles. Starting, stopping, and sharp turns induce inertial and centrifugal forces that can send the wheelchair and its occupant careening around the adjacent space, with obvious risk of injury. The occupant may well have limited use of his arms to protect himself. To remove this danger, coupling devices have been used to releasably secure the wheelchair in place. These retainers are secured to the vehicle structure, and may be adapted to grasp the rim and tire of a wheelchair that is backed into engagement with the device. These couplings are presently available, but some design problems have remained. This invention presents an improvement on the Barecki Patent No. 4,113,270 with regard to cost and reliability.
A clear indication of the unlocked condition of the coupling has not heretofore been provided. It must be kept in mind that the position of the jaws may well be obscured, as the coupling is normally behind the occupant of the chair. It also may not be clearly visible because of the presence of the wheel rim, tire, and the adjacent vehicle structure. Some previous coupling devices have incidentally involved locking systems in which a locking component moves into view when the locking action is completed, but this is not the situation that causes the most trouble. The occupant, or the vehicle attendant, should have a very clear signal presented to him when the locking action has not been completed. Regrettable accidents have taken place when a superficial glance at the coupling device suggests that the chair is firmly secured, when later it appears that this is not the case. Released from the grasp of the coupling, the occupant is at the mercy of whatever may happen to him. The emergence of part of a locking pin in the fully locked condition of the device, as is characteristic of the device described in the Downing, et al, Patent Number 4,062,209, does not appear to be adequate. The absence of such a projection does not apparently call sufficient attention to the danger that is present.
Another problem has been in the position of the unlocking actuator that the occupant or a vehicle attendant must operate in order to release the wheelchair. The direction of the force necessary to effect this release is important. An occupant with at least some use of his arms should be able to release his chair, and thus be less dependent on the help of others. It is very advantageous to have the force necessary to operate the release take place in a direction that will move the chair out of the grasp of the coupling device. Escape from the device therefore can be effected as a single operation, and with one hand. When the unlocking force is in a different direction from that which will move the vehicle away from the device, such movement must be generated at the same time that the device is being unlocked. This produces a two-handed operation that frequently requires the assistance of others. Refinements have also been needed to provide a sturdy structure that can be manufactured and installed easily, with consequent economy.